Roll-up/roll-down doors are well-known, in many configurations. The invention is concerned with the type of door which comprises horizontal slats or segments, the ends of which run in tracks or guideways. The door is operable, generally, by means of an electric motor. The door is counterbalanced by a spring coiled around an actuation spindle, or by counterweights, etc.
A problem that can arise with such doors is that the slats may snag in the guideways. If one end of a slat becomes snagged in the guideway, while the door is descending, the slat will tilt. The other end of the slat continues descending, and, because of the tilt, reaches an angle at which the end of the slat is no longer contained within the guideway. From then on, the slats tend to spill out of the guideways.
When that happens, inevitably some of the slats will become twisted, and some of the hinges between the slats will be strained. Even if the slats can be put back in the guideways, after such an occurrence, the door is likely never to operate smoothly, and also to become increasingly prone to become snagged again in the guideways.
The invention is aimed at providing a tilt-detecting device, which may be attached to the door, and which is effective to detect the onset of the slat-snagged condition, and to arrest the motion of the door before any damage is done, and especially before the slats can spill out of the guideways.
1. General Features of the Invention
The invention provides a tilt-detecting device, which is attached preferably to the bottom slat of a hinged-slat type, raisable/lowerable door. The device includes means for detecting when a slat of the door undergoes a tilt of more than a predetermined angle Q, in the left/right sense of the door, the angle Q lying in the plane of the door. The device also includes a means for arresting motion of the door upon detecting, and in response to, the said tilt.
The device of the invention permits the door to be used in the normal way, in which the degree of attention paid to the door itself, by the users, is extremely casual, and servicing of the door is, as is all too often the case, neglected.
2. The Invention in Relation to the Prior Art
There have been many examples of various arrangements of detectors for detecting the position of a door. These have concentrated on the degree of the door's opening and closing, for many purposes, including: control of the powered open/close motor of the door of a factory; detecting unauthorised entry; fire control; automatic ventilation; and so on. Often, these sensors have detected changes in the angular position of the door (or window).
The invention, by contrast, detects the angle of tilt of the door, i.e the tilt in the left/right sense, in the plane of the door.